Polish and simplyfy STUN code, move STUN code to GNUNET_NAT_

1 files changed, 463 insertions, 1 deletions

diff --git a/src/nat/nat_stun.c b/src/nat/nat_stun.c
index 06ed9261f..490a11257 100644
--- a/src/nat/nat_stun.c
+++ b/src/nat/nat_stun.c
@@ -34,6 +34,468 @@
  *
  *
  * @file nat/nat_stun.c
- * @brief Testcase for STUN library
+ * @brief Functions for STUN functionality
  * @author Bruno Souza Cabral
  */
+
+#include "platform.h"
+#include "gnunet_util_lib.h"
+#include "gnunet_program_lib.h"
+#include "gnunet_scheduler_lib.h"
+#include "gnunet_nat_lib.h"
+
+
+#include "nat_stun.h"
+
+#define LOG(kind,...) GNUNET_log_from (kind, "stun", __VA_ARGS__)
+
+
+
+/**
+ * Handle to a request given to the resolver.  Can be used to cancel
+ * the request prior to the timeout or successful execution.  Also
+ * used to track our internal state for the request.
+ */
+struct GNUNET_NAT_StunRequestHandle {
+
+     /**
+     * Handle to a pending DNS lookup request.
+     */
+     struct GNUNET_RESOLVER_RequestHandle *dns_active;
+
+
+     /**
+     * Handle to the listen socket
+     */
+     struct GNUNET_NETWORK_Handle * sock;
+
+     /**
+     * Stun server address
+     */
+     char *stun_server ;
+
+     /**
+     * STUN port
+     */
+     int stun_port;
+
+};
+
+
+
+/* here we store credentials extracted from a message */
+struct StunState {
+     uint16_t attr;
+};
+
+
+/**
+ * Convert a message to a StunClass
+ *
+ * @param msg the received message
+ * @return the converted StunClass
+ */
+static int decode_class(int msg)
+{
+     return ((msg & 0x0010) >> 4) | ((msg & 0x0100) >> 7);
+}
+
+/**
+ * Convert a message to a StunMethod
+ *
+ * @param msg the received message
+ * @return the converted StunMethod
+ */
+static int decode_method(int msg)
+{
+     return (msg & 0x000f) | ((msg & 0x00e0) >> 1) | ((msg & 0x3e00) >> 2);
+}
+
+/**
+ * Encode a class and method to a compatible STUN format
+ *
+ * @param msg_class class to be converted
+ * @param method method to be converted
+ * @return message in a STUN compatible format
+ */
+static int encode_message(StunClasses msg_class, StunMethods method)
+{
+     return ((msg_class & 1) << 4) | ((msg_class & 2) << 7) |
+            (method & 0x000f) | ((method & 0x0070) << 1) | ((method & 0x0f800) << 2);
+}
+
+/**
+ * Print a class and method from a STUN message
+ *
+ * @param msg
+ * @return string with the message class and method
+ */
+static const char *stun_msg2str(int msg)
+{
+
+     const struct { enum StunClasses value; const char *name; } classes[] = {
+             { STUN_REQUEST, "Request" },
+             { STUN_INDICATION, "Indication" },
+             { STUN_RESPONSE, "Response" },
+             { STUN_ERROR_RESPONSE, "Error Response" },
+             { 0, NULL }
+     };
+
+     const struct { enum StunMethods value; const char *name; } methods[] = {
+             { STUN_BINDING, "Binding" },
+             { 0, NULL }
+     };
+
+     static char result[32];
+     const char *msg_class = NULL;
+     const char *method = NULL;
+     int i;
+     int value;
+
+     value = decode_class(msg);
+     for (i = 0; classes[i].name; i++) {
+          msg_class = classes[i].name;
+          if (classes[i].value == value)
+               break;
+     }
+     value = decode_method(msg);
+     for (i = 0; methods[i].name; i++) {
+          method = methods[i].name;
+          if (methods[i].value == value)
+               break;
+     }
+     snprintf(result, sizeof(result), "%s %s",
+              method ? : "Unknown Method",
+              msg_class ? : "Unknown Class Message");
+     return result;
+}
+
+/**
+ * Print attribute name
+ *
+ * @param msg with a attribute type
+ * @return string with the attribute name
+ */
+static const char *stun_attr2str(int msg)
+{
+     const struct { enum StunAttributes value; const char *name; } attrs[] = {
+             { STUN_MAPPED_ADDRESS, "Mapped Address" },
+             { STUN_RESPONSE_ADDRESS, "Response Address" },
+             { STUN_CHANGE_ADDRESS, "Change Address" },
+             { STUN_SOURCE_ADDRESS, "Source Address" },
+             { STUN_CHANGED_ADDRESS, "Changed Address" },
+             { STUN_USERNAME, "Username" },
+             { STUN_PASSWORD, "Password" },
+             { STUN_MESSAGE_INTEGRITY, "Message Integrity" },
+             { STUN_ERROR_CODE, "Error Code" },
+             { STUN_UNKNOWN_ATTRIBUTES, "Unknown Attributes" },
+             { STUN_REFLECTED_FROM, "Reflected From" },
+             { STUN_REALM, "Realm" },
+             { STUN_NONCE, "Nonce" },
+             { STUN_XOR_MAPPED_ADDRESS, "XOR Mapped Address" },
+             { STUN_MS_VERSION, "MS Version" },
+             { STUN_MS_XOR_MAPPED_ADDRESS, "MS XOR Mapped Address" },
+             { STUN_SOFTWARE, "Software" },
+             { STUN_ALTERNATE_SERVER, "Alternate Server" },
+             { STUN_FINGERPRINT, "Fingerprint" },
+             { 0, NULL }
+     };
+     int i;
+
+     for (i = 0; attrs[i].name; i++) {
+          if (attrs[i].value == msg)
+               return attrs[i].name;
+     }
+     return "Unknown Attribute";
+}
+
+
+/**
+ * Fill the stun_header with a random request_id
+ *
+ * @param state, STUN attribute type
+ * @param attr , the actual attribute
+ *
+ * @param req, stun header to be filled
+ */
+static int stun_process_attr(struct StunState *state, struct stun_attr *attr)
+{
+     LOG (GNUNET_ERROR_TYPE_INFO,
+          "Found STUN Attribute %s (%04x), length %d\n",
+          stun_attr2str(ntohs(attr->attr)), ntohs(attr->attr), ntohs(attr->len));
+
+     switch (ntohs(attr->attr)) {
+          case STUN_MAPPED_ADDRESS:
+          case STUN_XOR_MAPPED_ADDRESS:
+          case STUN_MS_XOR_MAPPED_ADDRESS:
+               break;
+          default:
+               LOG (GNUNET_ERROR_TYPE_INFO,
+                    "Ignoring STUN Attribute %s (%04x), length %d\n",
+                    stun_attr2str(ntohs(attr->attr)), ntohs(attr->attr), ntohs(attr->len));
+
+     }
+     return 0;
+}
+
+
+
+/**
+ * Fill the stun_header with a random request_id
+ *
+ * @param req, stun header to be filled
+ */
+static void
+generate_request_id(struct stun_header *req)
+{
+     int x;
+     req->magic = htonl(STUN_MAGIC_COOKIE);
+     for (x = 0; x < 3; x++)
+          req->id.id[x] = GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_NONCE,
+                                                    UINT32_MAX);
+}
+
+
+/**
+ * Extract the STUN_MAPPED_ADDRESS from the stun response.
+ * This is used as a callback for stun_handle_response
+ * when called from stun_request.
+ *
+ * @param st, pointer where we will set the type
+ * @param attr , received stun attribute
+ * @param arg , pointer to a sockaddr_in where we will set the reported IP and port
+ * @param magic , Magic cookie
+ *
+ * @return 0 on sucess, other value otherwise
+ */
+static int
+stun_get_mapped(struct StunState *st, struct stun_attr *attr,struct sockaddr_in *arg, unsigned int magic)
+{
+    struct stun_addr *returned_addr = (struct stun_addr *)(attr + 1);
+    struct sockaddr_in *sa = (struct sockaddr_in *)arg;
+    unsigned short type = ntohs(attr->attr);
+
+    switch (type) {
+        case STUN_MAPPED_ADDRESS:
+            if (st->attr == STUN_XOR_MAPPED_ADDRESS ||
+                st->attr == STUN_MS_XOR_MAPPED_ADDRESS)
+                return 1;
+            magic = 0;
+            break;
+        case STUN_MS_XOR_MAPPED_ADDRESS:
+            if (st->attr == STUN_XOR_MAPPED_ADDRESS)
+                return 1;
+            break;
+        case STUN_XOR_MAPPED_ADDRESS:
+            break;
+        default:
+            return 1;
+    }
+    if (ntohs(attr->len) < 8 && returned_addr->family != 1) {
+        return 1;
+    }
+
+    st->attr = type;
+    sa->sin_port = returned_addr->port ^ htons(ntohl(magic) >> 16);
+    sa->sin_addr.s_addr = returned_addr->addr ^ magic;
+    return 0;
+}
+
+
+/**
+ * Handle an incoming STUN message, Do some basic sanity checks on packet size and content,
+ * try to extract a bit of information, and possibly reply.
+ * At the moment this only processes BIND requests, and returns
+ * the externally visible address of the request.
+ * If a callback is specified, invoke it with the attribute.
+ *
+ * @param data, the packet
+ * @param len, the length of the packet
+ * @param arg, sockaddr_in where we will set our discovered packet
+ *
+ * @return, 0 on OK, -1 if the packet is invalid ( not a stun packet)
+ */
+int
+GNUNET_NAT_stun_handle_packet(const uint8_t *data, size_t len,struct sockaddr_in *arg)
+{
+     struct stun_header *hdr = (struct stun_header *)data;
+     struct stun_attr *attr;
+     struct StunState st;
+     int ret = STUN_IGNORE;
+
+     uint32_t advertised_message_size;
+     uint32_t message_magic_cookie;
+
+
+     /* On entry, 'len' is the length of the udp payload. After the
+          * initial checks it becomes the size of unprocessed options,
+          * while 'data' is advanced accordingly.
+          */
+     if (len < sizeof(struct stun_header)) {
+          LOG (GNUNET_ERROR_TYPE_INFO,
+               "STUN packet too short (only %d, wanting at least %d)\n", (int) len, (int) sizeof(struct stun_header));
+          GNUNET_break_op (0);
+          return -1;
+     }
+     /* Skip header as it is already in hdr */
+     len -= sizeof(struct stun_header);
+     data += sizeof(struct stun_header);
+
+     /* len as advertised in the message */
+     advertised_message_size = ntohs(hdr->msglen);
+
+     message_magic_cookie = ntohl(hdr->magic);
+     /* Compare if the cookie match */
+     if(STUN_MAGIC_COOKIE != message_magic_cookie){
+          LOG (GNUNET_ERROR_TYPE_INFO,
+               "Invalid magic cookie \n");
+          GNUNET_break_op (0);
+          return -1;
+     }
+
+
+     LOG (GNUNET_ERROR_TYPE_INFO, "STUN Packet, msg %s (%04x), length: %d\n", stun_msg2str(ntohs(hdr->msgtype)), ntohs(hdr->msgtype), advertised_message_size);
+
+
+     if (advertised_message_size > len) {
+          LOG (GNUNET_ERROR_TYPE_INFO, "Scrambled STUN packet length (got %d, expecting %d)\n", advertised_message_size, (int)len);
+          GNUNET_break_op (0);
+         return -1;
+     } else {
+          len = advertised_message_size;
+     }
+     /* Zero the struct */
+     memset(&st,0, sizeof(st));
+
+     while (len > 0) {
+          if (len < sizeof(struct stun_attr)) {
+               LOG (GNUNET_ERROR_TYPE_INFO, "Attribute too short (got %d, expecting %d)\n", (int)len, (int) sizeof(struct stun_attr));
+               GNUNET_break_op (0);
+               break;
+          }
+          attr = (struct stun_attr *)data;
+
+          /* compute total attribute length */
+          advertised_message_size = ntohs(attr->len) + sizeof(struct stun_attr);
+
+          /* Check if we still have space in our buffer */
+          if (advertised_message_size > len ) {
+               LOG (GNUNET_ERROR_TYPE_INFO, "Inconsistent Attribute (length %d exceeds remaining msg len %d)\n", advertised_message_size, (int)len);
+               GNUNET_break_op (0);
+               break;
+          }
+
+
+         stun_get_mapped(&st, attr, arg, hdr->magic);
+
+          if (stun_process_attr(&st, attr)) {
+               LOG (GNUNET_ERROR_TYPE_INFO, "Failed to handle attribute %s (%04x)\n", stun_attr2str(ntohs(attr->attr)), ntohs(attr->attr));
+               break;
+          }
+          /* Clear attribute id: in case previous entry was a string,
+                   * this will act as the terminator for the string.
+                   */
+          attr->attr = 0;
+          data += advertised_message_size;
+          len -= advertised_message_size;
+     }
+
+     return ret;
+}
+
+
+
+/**
+ * Try to establish a connection given the specified address.
+ *
+ * @param cls our `struct GNUNET_NAT_StunRequestHandle *`
+ * @param addr address to try, NULL for "last call"
+ * @param addrlen length of @a addr
+ */
+static void
+stun_dns_callback (void *cls,
+                           const struct sockaddr *addr,
+                           socklen_t addrlen) {
+
+
+     struct GNUNET_NAT_StunRequestHandle *request = cls;
+
+     struct stun_header *req;
+     uint8_t reqdata[1024];
+     int reqlen;
+     struct sockaddr_in server;
+
+     if(NULL == request) {
+          LOG (GNUNET_ERROR_TYPE_INFO, "Empty request\n");
+          return;
+     }
+
+     if (NULL == addr) {
+          request->dns_active = NULL;
+          LOG (GNUNET_ERROR_TYPE_INFO, "Error resolving host %s\n", request->stun_server);
+          return;
+     }
+
+
+     memset(&server,0, sizeof(server));
+     server.sin_family = AF_INET;
+     server.sin_addr = ((struct sockaddr_in *)addr)->sin_addr;
+     server.sin_port = htons(request->stun_port);
+
+
+     /*Craft the simplest possible STUN packet. A request binding*/
+     req = (struct stun_header *)reqdata;
+     generate_request_id(req);
+     reqlen = 0;
+     req->msgtype = 0;
+     req->msglen = 0;
+     req->msglen = htons(reqlen);
+     req->msgtype = htons(encode_message(STUN_REQUEST, STUN_BINDING));
+
+     /* Send the packet */
+     if (-1 == GNUNET_NETWORK_socket_sendto (request->sock, req, ntohs(req->msglen) + sizeof(*req),
+                                             (const struct sockaddr *) &server, sizeof (server)))
+     {
+          GNUNET_log_strerror (GNUNET_ERROR_TYPE_WARNING, "Fail to sendto");
+     }
+
+}
+
+
+/**
+ * Make Generic STUN request and
+ * Send a generic stun request to the server specified using the specified socket.
+ * possibly waiting for a reply and filling the 'reply' field with
+ * the externally visible address.
+ *c
+ * @param server, the address of the stun server
+ * @param port, port of the stun server
+ * @param sock the socket used to send the request
+ * @return GNUNET_NAT_StunRequestHandle on success, NULL on error.
+ */
+struct GNUNET_NAT_StunRequestHandle *
+GNUNET_NAT_stun_make_request(char * server, int port, struct GNUNET_NETWORK_Handle * sock)
+{
+
+     struct GNUNET_NAT_StunRequestHandle *rh;
+
+     rh = GNUNET_malloc (sizeof (struct GNUNET_NAT_StunRequestHandle));
+     rh->sock = sock;
+
+     char * server_copy = GNUNET_malloc (1 + strlen (server));
+     if (server_copy) {
+        strcpy (server_copy, server);
+     }else{
+         GNUNET_log_strerror (GNUNET_ERROR_TYPE_WARNING, "Failed to allocate string");
+         return NULL;
+     }
+
+     rh->stun_server = server_copy;
+     rh->stun_port = port;
+     rh->dns_active = GNUNET_RESOLVER_ip_get (rh->stun_server, AF_INET,
+                                              GNUNET_CONNECTION_CONNECT_RETRY_TIMEOUT,
+                                              &stun_dns_callback, rh);
+
+
+     return rh;
+}
\ No newline at end of file